1. Field of the Invention (Technical Field)
The present invention relates to valves and regulators for controlling the flow of fluids, particularly gases, and more specifically to valves for more safely regulating the flow of oxygen gas.
2. Background Art
Oxygen is widely used in many medical and industrial applications. When a portable source of oxygen is required, it is almost universally supplied in the form of molecular oxygen (O2) under pressure in a cylindrical steel or aluminum container. Oxygen also commonly is transported in such cylinders. The cylinders are equipped with a valve, used to open and close the cylinder for emptying and refilling. A pressure regulator often also is attached to the cylinder valve.
Oxygen cylinder valves, as they exist today, have been implicated in numerous fire incidents with sometimes catastrophic results. When a cylinder valve seat ignites, the attached regulator or manifold system is subjected to strong kindling chain mechanisms that will often lead to fires downstream of the cylinder valve.
The “plug type” cylinder valves presently in common use comprise a rotating threaded seat plug that translates due to the rotation of a hand wheel mounted on the top of the valve itself. The plug incorporates a relatively large nonmetallic seat. The seat is subjected to strong flow impingement during oxygen gas discharge from the cylinder, due to the seat's orientation above the valve nozzle. Further, due to the rotating seat mechanism, the seat often is subjected to strong frictional interference with the valve nozzle. Both of these features are undesirable to prudent persons aware of the fire hazards of handling oxygen cylinders. Conventional known valves are also “dirty,” generating large amounts of undesirable debris due to their mode of operation (i.e., rotating seat and threads in the oxygen wetted portion of the valve). This debris often deposits in the nonmetallic seat itself and increases the frictional interactions during valve opening and closing.
These valves most often utilize a nylon main seat although both polyphenylene oxide (PPO) and polychlorotrifluoroethylene (PCTFE) are also utilized. Both nylon and PPO exhibit poor to moderate compatibility based on present oxygen-compatibility rating test standards, and deliver a large amount of energy if ignited. PCTFE is considered an oxygen compatible material, but has a compressive modulus that is insufficient to withstand the torques that are often applied by the manual closing of conventional valves. As a result, PCTFE seated plug-valves often exhibit significant extrusion and recently have been implicated in a large number of fires. The extruded seat increases the surface-area-to-volume ratio for oxygen gas impingement during discharge, and is believed to greatly increase vulnerability of the seat to hazardous flow friction ignition. Further, many of the materials in use with known valves seats generate highly toxic gases when they burn.
There also is a need for an apparatus that combines the function of on-off valving with the flow adjustment capabilities of a flow regulator.
The present invention is an advance over the Applicant's previous valve invention, which is described in pending U.S. patent application Ser. No. 09/872,233, entitled “Cylinder Valve and Bayonet Check Filter with Excess Flow Protection Feature”, filed May 31, 2001, now allowed. References herein to the “original design,” “original apparatus,” or “original device,” are to the apparatus disclosed in U.S. patent application Ser. No. 09/872,233, which is incorporated herein by reference.